Force applying device



y 9, 1968 A. F. LlNDB ERG 3,391,581

FORCE APPLYING DEVICE 42. FIG. 2

Filed Sept. 14, 1966 FIG. 4 42 34 Q34 42 FIG 3 FIG. 5

FIG. 8

FIG. IO

'mvsm-on ARTHUR F. LINDBERG ATTORNE United States Patent 3,391,581 FORCE APPLYING DEVICE Arthur F. Lindherg, Chicago, Ill., assignor to Teletype Corporation, Skokie, 111., a corporation of Delaware Filed Sept. 14, 1966, Ser. No. 579,377 14 Claims. (Cl. 74-526) ABSTRACT OF THE DISCLOSURE A device for applying retarding forces to moving objects comprising a lever having a hooked end for engagement by the object, a flat surface extending from the hooked end, a spring attaching hole formed through the lever adjacent the fiat surface and a curved surface that terminates in a tip; a frame; a pre-loaded, helical tension spring connected between the frame and the spring attaching hole on the lever, and three reaction members all mounted on the frame, one position in engagement with the flat surface, one positioned in engagement with the curved surface and one in engagement with the tip of the curved surface of the lever.

This invention relates to energy storage devices and more particularly to devices for applying a predetermined amount of force to a moving object.

In a telegraph keyboard such as that shown in Patent No. 2,607,848, granted to W. J. Zenner on Aug. 19, 1952, a mechanical lever or code bar is released for movement from one position to another under the urging of a spring. Such a lever tends to bounce upon arriving at its terminal position, since the kinetic energy of the moving lever cannot be dissipated except in impulse or by a speed-dependent damper. Such a damper does not necessarily apply its damping effect at the most advantageous point in the levers motion.

Therefore, it is an object of the present invention to apply a measured amount of force to a moving object.

It is another object of the present invention to apply a force to a moving object at a predetermined point in its motion and to reduce this force to Zero before the object stops moving.

It is a further object of the present invention to apply a retarding force to a moving object over a predetermined length of the travel of the moving object.

According to the preferred embodiment of the invention as applied to a telegraph keyboard, a floating lever is spring-urged into engagement with a plurality of reaction supports and is maintained in an idle position by a stop post. A code bar on the keyboard is spring-urged to move in one direction when released by a key lever. As the code bar travels in that direction, a depending portion of it comes into engagement with an arm of the lever and disengages the lever from the stop post. The spring force on the lever and the reaction forces from the reaction supports determine the force exerted by the lever on the code bar. As the code bar moves the lever, the angle of application of one of the reaction forces changes due to a curvature of the support surface, resulting in a decrease in the force applied by the floating lever to the code bar until this force becomes substantially zero. After the force applied to the code bar becomes substantially zero, the direction of application of the one reaction force ceases to change as the code bar continues moving; and the force applied by the lever to the code bar remains negligible.

The present invention and its objects will be more fully understood from the following detailed description when read in connection with the accompanying drawings in which:

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FIG. 1 is a view of the retarding lever urged by a spring into engagement with its reaction supports and the stop post;

FIGS. 2, 4, 6, 8, and 10 are force diagrams representing the forces applied to the lever by its spring and its reaction supports and the resultant force applied by the lever to the code bar or to its own stop post in the various positions of the lever;

FIGS. 3, 5, and 7 are partial views of the lever and one of its reaction supports showing in steps the changes in the point of contact between the reaction support and the lever as the lever follows the code bar.

FIG. 9 is a view of the lever and its reaction supports at the terminal end of the motion of the code bar.

Referring now to the drawings wherein like reference numbers designate the same parts throughout the several views and referring more particularly to FIG. 1, a fragmental portion of a code bar 20 is shown moving leftwardly and is representative of any one of the code bars shown in the Zenner patent mentioned above. This code bar 20 is selectively released by the key levers of the keyboard mechanism for movement under the urging of a spring (not shown). A floating lever 25 is urged generally to the right and downwardly by a tension spring 30 which is attached to a spring post 31 that is secured to the framework of the telegraph keyboard mechanism. Two reaction supports 32 and 33 are also fixedly mounted on the framework of the keyboard, and lever 25 tends to be wedged between them. In the position shown, however, lever 25 is still free to rotate in the clockwise direction and move to the right under the urging of the spring 30 and is prevented from doing so only by a stop post 34 which determines the rightmost position of the lever 25. An arm 36 of lever 25 carries a head 35 that is interposed in the path of movement of an appendage 37 on code bar 20. Before the instant that appendage 37 moves into engagement with head 35 of arm 36, floating lever 25 not yet having been disengaged from post 34, four vector forces are applied to the lever 25. One of these is applied by the spring 30, and two others are applied by the supports 32 and 33. The fourth force is supplied by the stop post 34 for maintaining the lever 25 in static equilibrium. The reaction forces from supports 32 and 33 and from stop post 34 are all applied to lever 25 in directions that are substantially perpendicular to the tangents to the surfaces of the support members at their points of contact with the lever 25.

FIG. 2 is a diagram of these four static forces acting on lever 25 before appendage 37 on code bar 20 engages head 35 of lever 25. The spring force is shown as a vector 40 directed along the axis of the spring. A vector 41 represents the reaction force applied to lever 25 by reaction support 32 and is shown applied at the head of vector 40. A vector 42 representative of the reaction force applied by reaction support 33 to lever 25 is shown directed perpendicular to the tangent to support 33 at its point of contact with the lever 25 and is positioned at the head of vector 41. Well-known methods of resolution of vector diagrams and of vector addition yield the resultant fourth vector 43 which represents the force applied by the lever 25 on the stop post 34.

Referring now to FIG. 3, the positional relationships of the right-hand end of lever 25 to stop post 34 and reaction support 32 are the same as in FIG. 1, but it will be assumed that the appendage 37 on code bar 20' is now in contact with head 35 of lever 25 and is at the point of disengaging lever 25 from stop post 34. The resultant force derived from the vector addition is no longer applied to the stop post 34 but instead is applied to the code bar 20 of the keyboard mechanism. The force diagram of FIG. 4 shows the change in the reaction vectors that takes place when the appendage 37 on code bar engages the head 35 of lever 25. The force vector 40 of the spring remains substantially the same, but the reaction vector 41 from reaction support 32 increases due to the torque moment now applied to lever because of the difference in the point of application on the lever 25 of the resultant force from the code bar 20 instead of from the stop post 34. Similarly, vector 42 is larger in order to oppose the greater reaction vector 41. These three forces, by vector addition, result in a vector 44 which represents the force that is applied by the head 35 of lever 25 to the appendage 37 of code bar 20, tending to impede the leftward movement of code bar 20.

Referring now to FIG. 5, it will be seen that as the code bar continues to travel leftwardly it carries lever 25 with it, disengaging the right-hand end of lever 25 from stop post 34, and causing lever 25 to rock counterclockwise, with the point of engagement with reaction support 32 moving along the surface of that support in a clockwise direction. This point of engagement is a smallradius tip 59 on the right-hand end of lever 25. The tangent to curved reaction support 32 at the point of contact tip 50 of lever 25 and reaction support 32 now extends in a different direction than in FIG. 3 at which code bar 20 and lever 25 were at an earlier point in their cycle of operation. Since the reaction force from reaction support 32 is always directed substantially perpendicular to this tangent, and therefore, radially of the cylindrical support 32, the reaction force acting upon lever 25 from reaction support 32 is applied to lever 25 in a different direction.

The effect of this change of direction is more fully shown in FIG. 6 wherein the vector 40 from the spring is substantially the same as it was in FIGS. 2 and 4; but vector 41, which represents the reaction force from support 32, is applied in a different direction. Vector 42, when combined with vectors 41 and 40, results in a substantially reduced force vector 44 that is applied to the code bar 20 by lever 25.

Referring now to FIG. 7 which is also a partial view showing the reaction support 32 and the lever 25, the tip 50 of lever 25 has now traveled sufficiently along the surface of reaction support 32 that the reaction force vector 41 (FIG. 8) from reaction support 32 is applied in a direction which results in the application of no retarding force on code bar 20. In FIG. 8, vector 40, applied to lever 25 by the spring 30, is still applied in substantially the same direction and with substantially the same magnitude as before.

The slope of vector 41 has decreased, and the angle between it and vector 42 has increased to a corresponding extent, so that the addition of vectors 40, 41 and 42 results in the availability of no net force on lever 25 for application to code bar 20. This is evidenced by the fact that the three vectors form a triangle. In this position, lever 25 is in static equilibrium, since the forces applied by the spring 30 and the reaction supports 32 and 33 perfectly balance each other. So long as the point of contact between reaction support 32 and lever 25 does not move to a different location on reaction support 32, the vector diagram shown in FIG. 8 will not change substantially even though head of lever 25 is moved farther to the left by code bar 20.

FIG. 9 shows the lever 25 in a position wherein tip 50 of lever 25 is in a substantially different position from that shown in FIG. 7. At all times, some part of lever 25 is in contact with support 32. It can be seen that the continued leftward movement of head 35 of lever 25 causes the point of contact between reaction support 32 and lever 25 to change, not on support 32, but on the large-radius curved surface 51 of lever 25. Since in FIG. 9 the tangent to reaction support 32 at its point of contact with lever 25 has not changed substantially from the position shown in FIG. 7, the vector 41 of FIG. 10 is directed substantially the same as it is in FIG. 8 so that there is still no force applied to code bar 20, even though code bar 20 may have continued to move the head 35 of arm 36 of lever 25 to the left.

It can be seen, therefore, that code bar 29 experiences a substantial, initial retarding force as it moves to the left. This force is maximum when code bar 20 first engages head 35 of lever 25, but the force is quickly reduced as point of lever 25 moves around the curved surface of reaction support 32. This movement of point of lever 25 changes the direction of application of the reaction vector 41 that is applied to lever 25 by reaction support 32 until there is no net force available for application to code bar 20. Further movement of code bar 20 and lever 25 results in no further change in the direction of application of vector 41, resulting in the continued absence of opposition to movement of code bar 20.

Initial leftward movement of head 35 of lever 25 causes lever 25 to move leftwardly and to stretch spring 30 slightly. Therefore, the energy that is absorbed from code bar 20 is stored in spring 30. After sufficient leftward movement lever 25 ceases leftward translational motion; and further leftward movement of code bar 20 causes counterclockwise rotation of lever 25 about spring 30 with no additional stretching of spring 30'. If no further stretching of spring 30 occurs, no further energy can be absorbed from code bar 26.

A rounded surface on lever 25 in contact with support 33 can cause lever 25 to rotate accurately about the spring 30 in the condition shown in FIG. 9 if spring 30 is attached to lever 25 at the center of curvature of this rounded surface and of curved surface 51. However, since friction actually exists between lever 25 and supports 32 and 33, it is preferable to make the surface of lever 25 flat where it touches support 33 and to attach spring 30 to lever 25 at a point below the center of curvature of curved surface 51. This theoretically produces a torsional moment on lever 25 that results in a negative force between head 35 of lever 25 and code bar 20. Suitable adjustment of the location of spring 30 on lever 25 and of the angle of the surface on lever 25 that is in contact with support 33 yields a negative force which will compensate for the frictional forces acting upon lever 25. Therefore, only a negligible force need actually be applied to lever 25 in the position shown in FIG. 9 to move head 35 to the left.

When code bar 20 is reset to its rightmost position, lever 25 can be reset to its initial position by moving head 35 rightwardly until lever 25 reaches a position at which a positive force would exist between head 35 and depending portion 37 of code bar 20. This force is then sufiicient to return lever 25 to stop post 34. Rightward movement of head 35 can be accomplished by another depending portion (not shown) on code bar 20 that is located to the left of head 35 and which carries head 35 to the above-mentioned position of lever 25 as code bar 20 reaches its rightmost position.

Although only one embodiment of the invention is shown in the drawings and described in the foregoing speci. cation, it will be understood that invention is not limited to the specific embodiment described, but is capable of modification and rearrangement and substitution of parts and elements without departing from the spirit of the invention.

What is claimed is:

1. A device for applying a force to an object CHXlPl'lS- ing:

a lever;

means for applying a substantially steady force to the lever;

means for applying reaction forces to the lever oppos ing the steady-force-applying means and causing the lever to be held in place;

means on the lever for engaging the object and for applying a force thereto; and

means responsive to relative movement between the lever and the object for changing the direction of application of one of the reaction forces applied to the lever whereby the force applied by the lever to the object is changed.

2. A device according to claim 1 wherein the means for applying a substantially-steady force to the lever is a tension spring attached to the lever and the means for applying reaction forces to the lever are a plurality of support surfaces against which the spring urges the lever whereby these surfaces support the lever by applying reaction forces thereto.

3. A device according to claim 2 wherein the means for engaging the object is an arm extending from the lever into the path of relative movement between the lever and the object whereby the object engages the arm and carries the arm with it.

4. A device according to claim 2. wherein one of the supporting surfaces is curved and the means for changing the direction of application of one of the reaction forces comprises a small-radius bearing surface on the lever in engagement with the curved supporting surface, whereby the bearing surface on the lever moves along the curved supporting surface as the relative movement between the lever and the object causes the tangent of the curved supporting surface at the point of contact with the hearing surface to change direction.

5. A device according to claim 4 wherein there is provided:

a large-radius bearing surface on the lever adjacent to the small radius bearing surface for engagement with the curved supporting surface at a predetermined point in the relative movement of the lever and the object for substantially preventing further change of the point on the curved supporting surface Where the curved surface and the bearing surface on the lever make contact.

6. A device according to claim 1 comprising:

means responsive to further relative movement of the lever and the object for preventing further change of direction of application of said one of the reaction forces whereby the force applied by the lever to the object does not undergo further change of direction as the relative movement between the lever and the object continues.

7. A device for applying a force to a moving object comprising:

a. lever;

means for applying a substantially-steady force to the lever;

means for resisting a plurality of differently directed components of the force applied to the lever by the steady-force-applying means for holding the lever stationary;

means on the lever for engaging the moving object, for applying a force thereto and for subjecting the lever to movement by the moving object; and

means responsive to the movement of the lever by the moving object for changing the direction of one of the force components whereby the force applied by the lever to the moving object is changed.

8. A device according to claim 7 wherein the means for applying a substantially-steady force to the lever is a tension spring connected to the lever and the means for resisting the force components are a plurality of support surfaces against which the spring urges the lever.

9. A device according to claim 7 wherein the means for engaging the moving object is an arm of the lever extending into the path of movement of the moving object.

10. A device for applying a diminishing force to a movable object comprising:

a member having a portion engageable with the movable object;

energy supplying means for causing the member to exert a force upon the movable object; and

fixed supports for the member engaged thereby and disposed relative thereto to cause the exertion of force on the movable object to occur initially through substantially non-rotative displacement of the member and to diminish by gradual change of movement of the member to substantially rotative displacement.

11. A device according to claim 10 for applying a diminishing force to a movable object wherein the supplying means comprises means for biasing the member in a direction to cause the member yieldably to resist movement of the movable object and wherein the fixed supports cause the yielding of the member to occur initially as substantially a translational displacement and to change gradually to substantially rotative non-resistive displacement.

12. A force applying device including:

a frame;

a lever having a pair of surfaces at least on: of which is curved;

a spring connected between the frame and a point on the lever between the surfaces thereon, and

a pair of reaction members mounted on the frame and positioned for engagement with the surfaces of the lever.

13. The device according to claim 12 wherein the curved surface on the lever terminates in a tip and wherein one of the reaction members engages the tip.

14. The device according to claim 13 further including means on the lever for engaging an object upon relative movement of the lever and the object and upon engagement for initially moving the tip with respect to the one of the reaction members thereby applying the force of the spring to the object and for thereafter pivoting the lever about the point of attachment of the spring to the lever with the curved surface in engagement with the one of the reaction members thereby allowing the lever to move with the object without applying additional forces thereto.

References (Iited UNITED STATES PATENTS 4/1963 Voser 745l8 7/1963 Nilsson 74-518 

